Lubrication system for a compressor

ABSTRACT

In a first embodiment, the invention comprises supplanting the usual, single, electrically-operated, blowdown valve, located on the receiver/separator tank of a gas compressor system with a pair of valves operatively arranged in parallel. The one valve operates normally in the manner of the supplanted valve, albeit with reduced venting capacity, and the other is held closed on starting of the compressor. This restricts the venting of the tank and causes its quick pressurization, to induce prompt oil injection for the compressor. A sensor detects the injection oil temperature and when the latter has achieved a given setpoint, the other, vent-restricting valve is opened. Accordingly, the method comprises sensing the temperature of the oil injected into the compressor and holding one of the paired venting valves closed until the oil temperature reaches the aforesaid given or predetermined setpoint.

This invention pertains to lubrication systems for machines, and tomethods of improving lubricant injection in machines, and in particularto such lubrication systems for use in combination with a pump, gascompressor, gas expander or the like, and a method of improvinglubricant injection for a pumpless gas compressor.

In known gas compressors which have no oil pump, it is required that thereceiver/separator tanks have sufficient pressure therein to provideadequate oil injection on start up. However, this object is frustratedby the typical blowdown valve used with receiver/separator tanks.

To prevent compressor rumble during the unloaded mode of operation, itis a common practice to allow a small amount of "make-up" air to flowthrough the compressor. Typically, the make-up air is vented toatmosphere through a single, electrically-operated, blowdown valvelocated on the receiver/separator tank. In pumpless compressor systems,the unloaded tank pressure is maintained only high enough to preventrumble, thus minimizing power absorption during unloaded operation.

Start up, particularly low ambient starting, can be a problem for suchpumpless compressor systems where oil flow (which is dependent on tankpressure) must be established quickly in order to prevent oil starvationof the compressor.

It is an object of this invention to set forth a lubrication systemwhich will prevent oil starvation of a pumpless gas compressor on startup. It is also an object of this invention to set forth, in combinationwith a machine such as a pump, gas compressor, gas expander, or thelike, adapted to handle a working fluid, a lubrication system for themachine, comprising first means for conducting working fluid to saidmachine; second means for conducting working fluid and lubricant fromsaid machine; reservoir means for storing lubricant; and third meanscommunicating with said reservoir means and said machine for passinglubricant therethrough from said reservoir means to said machine;wherein said second means communicates with said reservoir means forpassing lubricant therethrough to said reservoir means; and furtherincluding means, coupled to one of said first and second means,operative for controllingly modulating the fluid conduct of said onemeans; means, coupled to one of said second and third means, for sensinga given condition of lubricant therein; and means, coupled to saidsensing means and said modulating means, responsive to a given setpointof said given condition, as sensed by said sensing means, for operatingsaid modulating means.

It is a further object of this invention to set forth a method ofimproving lubricant injection in a gas compressor system which has (a) agas compressor, (b) first means for admitting gas into the compressor,(c) second means for discharging gas and oil from the compressor, (d)third means for storing, under pressure, gas and oil discharged from thecompressor, (e) fourth means communicating with said storing means forinjecting oil, under pressure, into the compressor, and (f) fifth meansfor venting gas from said storing means, wherein said first means isoperative in a first mode for providing unrestricted gas admittance andin a second mode for throttling gas admittance, and said fifth means isoperative in a first mode for providing restrictive venting of gas andin a second mode for providing unrestricted venting of gas, said methodcomprising the steps of sensing the temperature of oil injected into thecompressor; and operating one of said first and fifth means in saidfirst operative mode thereof only until the injected oil achieves agiven, setpoint temperature.

Further objects of this invention as well as the novel features thereofwill become more apparent by reference to the following descriptiontaken in conjunction with the accompanying figures, in which:

FIG. 1 is a schematic diagram of a gas compressor system incorporating afirst embodiment of the invention; and

FIG. 2 is a schematic diagram of a gas compressor system, similar tothat of FIG. 1, which, however, incorporates an alternative, secondembodiment of the invention.

As shown in the figures, a gas compressor system 10, has a gascompressor 12 of the pumpless type in communication with areceiver/separator tank 14. The latter receives the compressed gasproduct of the compressor 12. It also stores therein injection oil, forthe compressor 12, which has been separated out from the compressed gasproduct. A line 16 communicates the lower end or reservoir portion ofthe tank 14 with the compressor oil injection access 18, and thecompressor 12 has a customary air inlet port 20. A discharge line 22 iscoupled to the tank and to a check valve 24 from which to supplycompressed gas for the end item use. In addition, the tank 14 has a pairof vent valves 26 and 28 communicating therewith in parallel. The firstof the valves 26 operates, as is well-known in the prior art, to ventthe tank 14 during the unloaded mode of operation of the compressor 12.However, its venting capacity is considerably less than that of a usual,prior art venting valve. The second valve 28, normally open, isoperated, according to the invention, depending upon the temperature ofthe oil injected into the compressor 12. When open (after temperaturesetpoint has been reached), it cooperates with valve 26 to provide acustomary venting capacity as is necessary to discharge "make-up" air.

Valve 28 is a solenoid-operated component, sold under the trademarkLucifer, by Sperry Vickers, a division of Sperry Corporation, 1401Crooks Road, Troy, Mich. 48084; the Lucifer valve 28 is identified bythe manufacturer by part number U322G2501BOR2.

A temperature sensor 30 is connected to a temperature switch 32, thesensor 30 being in sensing communication with the oil injected viaaccess 18. Sensor 30 and switch 32 are an integrated element sold byFenwal, Inc., 400 Main Street, Ashland, Mass. 01721 under the partnumber 08-810019-285/08-990000-085. The sensor 30/switch 32 is shownonly symbolically, functionally and sensingly coupled to the lubricationinjection of access 18. A source of electrical power 11 is conducted toa transformer 13, and from the latter, via lines 15 and 17, power issupplied to valve 28 and switch 32. The switch 32, therefore, is coupledto, and operative of, the valve 28. The latter is normally open, asnoted, and is closed when the start-up cycle for the compressor begins.In turn, the sensor 30 will not actuate the switch 32, to open the valve28, until some predetermined oil temperature setpoint is sensed. Whilethere may be other, suitable sources for a sensor and temperature switchcomponent, serving the functions of sensor 30 and switch 32, Fenwal,Inc., of 400 Main Street, Ashland, Mass., 01721 markets such a componentunder the part number 08-810019-285/08-990000-085.

At start-up of the compressor 12, the one valve 26 remains open(permitting air flow) and the other valve 28 is closed (no air flow).The closed valve 28 acts as an orifice restricting the exhaust air flowfrom the tank 14. This elevates the pressure in the tank 14 which, as aconsequence, quickly increases oil flow. The valve 28, as noted, iscontrolled by the temperature switch 32 actuated by the sensor 30 whichsenses the compressor oil injection temperature. When the injected oiltemperature reaches the predetermined or specified setpoint, indicatingsatisfactory oil flow, the sensor 30 opens the temperature switch 32,which opens the valve 28, causing the tank pressure to drop to thenormal, unloaded level.

An alternative embodiment of the invention is shown in FIG. 2 where sameor similar index numbers denote same or similar elements or componentsas in FIG. 1.

The second embodiment of the invention shown in assocition with a gascompressor system 10a in FIG. 2 has the usual, single, vent valve 26aconnected to the tank 14, but here the typical butterfly valve 34disposed in the air inlet duct 36 is bypassed. A bypass line 38 isarranged to shunt the butterfly valve 34, and intermediate the length ofthe line 38 there is a normally closed bypass valve 40. The valve 40 iscoupled to, and controlled by, the temperature switch 32 which isactuated depending upon the temperature level of the injected oil. Valve40 is very much like valve 28 (of FIG. 2), being solenoid-operated andalso being available from Sperry Vickers, or a like source.

At start-up of the compressor 12, the inlet bypass valve 40 is opened,thus allowing more make-up air to pass through the duct 36, and into andthrough the compressor, than normal. The increased make-up air causes anelevated pressure in the tank 14, which, in turn, increases oil flow tothe compressor. The bypass valve 40 is controlled by the temperatureswitch 32, the latter being controlled by the sensor 30 which senses thecompressor oil injection temperature. When the injected oil temperaturereaches the specified setpoint, indicating satisfactory oil flow, thetemperature switch 32 closes the valve 40, and the tank pressure dropsto the normal unloaded level.

In FIGS. 1 and 2 the valves 26, 28 and 26a are shown communicating withthe tank 14 via lines 42, and lines 44 conduct the compressed gasproduct and entrained oil to the tanks 14. Now then, it will be commonlyunderstood that lines 44 and 22 are provided for conducting workingfluid from the compressor 12, i.e., to supply the compressed gas productto the user or end item equipment. However, and for the purposes ofconstruing the appended claims, it must be recognized that valves 26, 28and 26a, and lines 44 and 42, in cooperation with tanks 14, alsocomprise means which similarly conduct working fluid and/or workingfluid and lubricant from the compressors 12. In neither embodiment ofthe invention is the common delivery means for the compressed gasproduct, i.e., lines 44 and 22, in conjuction with tanks 14, anydifferent from prior art arrangements. It is in the embodiment of FIG.1, however, where the otherwise common, venting conduct of working fluid(gas) from the compressor 12 is inventively altered by my teaching.

Each embodiment of the invention lends itself most readily toretrofitting of gas compressor systems. Clearly, with reference to FIG.1, it remains only to supplant the usual, single, receiver/separatortank vent valve with valves 26 and 28, the latter comprising, together,a venting capacity equal to that of such supplanted valve. Then, byincorporating the sensor 30 and switch 32, in operative coupling withthe access 18 and valve 28, the first embodiment of the invention is inplace. Similarly, the FIG. 2 embodiment employs a same sensor 30 andswitch 32, the latter operatively joined to the valve 40. The line 38,in which valve 40 is interposed, simply opens, at the opposite endsthereof, onto the opposite sides of the butterfly valve 34.

While I have described my invention in connection with specificembodiments thereof, and a particular method of its practice, it is tobe clearly understood that this is done only by way of example and notas a limitation to the scope of my invention as set forth in the objectsthereof and in the appended claims.

I claim:
 1. In combination with a gas compressor, a lubrication systemtherefor, comprising:first means for conducting gas to said compressor;and second means for conducting gas and lubricant from said compressor;wherein said second means includes reservoir means for storinglubricant; further including third means communicating with saidreservoir means and said compressor for passing lubricant therethroughfrom said reservoir means to said compressor; means, coupled to saidsecond means, operative for controllingly modulating the fluid conductof said second means; means, coupled to said third means, for directlycommunicating with lubricant therewithin, and for sensing a givencondition of lubricant therein; and means, coupled to said sensing meansand said modulating means, responsive to a given setpoint of said givencondition, as sensed by said sensing means, for operating saidmodulating means.
 2. Lubrication controlling means, for use incombination with a gas compressor, such gas compressor having firstmeans for conducting gas to said gas compressor, second means forconducting gas and lubricant from said gas compressor, said second meansincluding a reservoir for storing lubricant, and means for supplyinglubricant from said reservoir to said gas compressor, wherein saidlubricant controlling means comprises:means, for coupling thereof tosaid second means, operative for modulating the fluid conduct of saidsecond means; means for directly communicating with lubricant in saidlubricant-supplying means, for sensing a given condition of lubricant insaid supplying means; and means, for coupling thereof to said sensingmeans and said modulating means, responsive to a given setpoint of saidgiven condition, as sensed by said sensing means, for operating saidmodulating means.
 3. In combination with a gas compressor, a lubricationsystem therefor, comprising:first means for conducting gas to said gascompressor; and second means for conducting gas and lubricant from saidgas compressor; wherein said second means includes reservoir means forstoring lubricant; further including conduit means for supplyinglubricant from said reservoir means to said gas compressor; means,coupled to said second means, operative for controllingly modulating thefluid conduct of said second means; means, coupled to said conduitmeans, for directly communicating with lubricant therewithin, and forsensing a given condition of lubricant therein; and means, coupled tosaid sensing means and said modulating means, responsive to a givensetpoint of said given condition, as sensed by said sensing means, foroperating said modulating means.
 4. The combination, according to claim3, wherein:said second means comprises a fluid-conducting linecommunicating with said gas compressor, at one end thereof, and having agiven fluid-venting valve at the other end thereof; said modulatingmeans comprises another fluid-venting valve communicating with said lineand operative in parallel with said given valve.
 5. The combination,according to claim 4, wherein:said sensing means comprises a temperaturesensor for sensing temperature levels of lubricant; said operating meanscomprises means responsive to a given temperature of lubricant, assensed by said sensor, for operating said another valve.
 6. Thecombination, according to claim 5, wherein:said another valve isswitch-operative; and said operation means comprises a switchoperatively coupled to said another valve.